The economic optimization and viability of an enterprise depends on the ability to accurately analyze the relationship between the cost of materials, services, and labor that are input into the enterprise and the return that is achieved on the product that is output by the enterprise. In agribusiness industries that raise animals such as livestock, poultry, marine animals, etc., the inputs include the animal itself, food, shelter, and services. The output, of course, is the marketable tissue components of the processed animal. One of the most critical relationships in optimizing the economic margins of an enterprise is the relationship between the controllable and uncontrollable factors that affect the rate at which the animal and its tissue components grow and the final size of the animal at marketing age. Thus, it is important to have a value-based food chain model that describes the relationship between each of these factors and the rate of growth of a population of animals.
Variables affecting the growth and yield of edible tissue of animals can be divided into genetic and non-genetic categories. Genetic variables are fixed and are reflected by the growth potential of the individual type of animal of interest. It will be appreciated by those skilled in the art that the growth rate of a animal is never higher and only lower than the maximum potential. During its life, a animal seeks to achieve its genetic potential, but fails due to the impediment of non-genetic variables.
Non-genetic variables that are partially controllable by the commercial operator can be divided further into living factors and food factors. Living factors encompass environmental conditions such as temperature, humidity, animal density, ventilation, disease conditions, air quality, etc. Food factors encompass the types and digested amounts of material that are ingested by a animal. One skilled in the art will appreciate that food factors can be controlled in a commercial environment through nutrition. The food factor reflects a major portion of the cost during the growth period.
To maximize an enterprise's before tax net margin, many scientists have used models to simulate the growth of various types of animals. (see G. C. Emmans, "The Growth of Turkeys," 21 Recent Advances in Turkey Science, 135-166 (C. Nixey and T. C. Grey eds. 1989); H. Talpaz et al., "Dynamic Optimization Model for Feeding of Broilers," Agric. Sys, 121-132 (1986); H. Talpaz et al., "Economic Optimization of a Growth Trajectory for Broilers," 70 Amer. J. Ag. Econ., 382-390 (1988); P. E. Waibel et al., TURKS Program Agricultural Extension Service (University of Minnesota 1985)). It will be appreciated that the various models represent efforts to take into account the incredibly complex and diverse structure of living entities, as well as the innumerable variables that affect the living entities in their environment.
One model that is used to describe animal growth is the Gompertz curve (B. Gompertz, "On the Nature of the Function Expressive of the Law of Human Mortality, and on a New Mode of Determining the Value of Life Contingencies," Philos. Trans. Roy. Soc., 513-585 (1825)), which shows the current mass weight as a function of age with known constant parameters. Gompertz curves have been used to describe the growth of poultry only in terms of a singular factor or characteristic such as a genetic characteristic, a living condition, or a food factor (G. C. Emmans, "The Growth of Turkeys," 21 Recent Advances in Turkey Science, 135-166 (C. Nixey and T. C. Grey eds. 1989); R. M. Gous et al., "A Characterization of the Potential Growth Rate of Six Breeds of Commercial Broiler," 2 Proceedings of XIX World's Poultry Congress, 20-24 (Amsterdam, The Netherlands, September 1992); N. B. Anthony et al., "Comparison of Growth Curves of Weight Selected Populations of Turkeys, Quail and Chickens," 70 Poultry Sci., 13-19 (1991)). However, because all the parameters are independent from one to another among all the curves, each Gompertz curve can describe growth in terms of only one set of conditions.
Because of the complexity of a life form, there is a need for a model that describes growth alternatives in terms of a plurality of different conditions. Such a model would permit an accurate economic analysis that allows a commercial operator to simultaneously (non-repetitive) optimize the relationship between the conditions and growth. In turn, the production of living animals would be more easily controlled in order to optimize production and hence maximize economic return.